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From: shebs@utah-cs.UUCP (Stanley Shebs)
Newsgroups: net.ai,net.lang.lisp
Subject: Re: Common LISP style standards.
Message-ID: <3802@utah-cs.UUCP>
Date: Thu, 29-May-86 11:20:04 EDT
Article-I.D.: utah-cs.3802
Posted: Thu May 29 11:20:04 1986
Date-Received: Sat, 31-May-86 06:35:07 EDT
References: <2784@jhunix.UUCP> <3787@utah-cs.UUCP> <545@bcsaic.UUCP>
Reply-To: shebs@utah-cs.UUCP (Stanley Shebs)
Distribution: net
Organization: University of Utah CS Dept
Lines: 32
Xref: watmath net.ai:3549 net.lang.lisp:854

In article <545@bcsaic.UUCP> michaelm@bcsaic.UUCP (michael maxwell) writes:

>I'm in a little different boat, since we're using Franz rather than Common
>Lisp

I remember Franz (vaguely)... :-)

>A common situation we find ourselves in is the following.  We have a long list,
>and we wish to apply some test to each member of the list.  However, at some
>point in the list, if the test returns a certain value, there is no need to
>look further: we can jump out of processing the list right there, and thus
>save time.

Common Lisp provides "some", "every", "notany", and "notevery" functions
which all do variations of what you're asking for.  They take a predicate
and one or more sequences as arguments, and apply the predicate to each
element in the sequence, and may stop in the middle.  The behavior is
sufficiently specified for you to use side effects in the predicate.
BTW, if these four functions weren't around, Common Lisp would be smaller.

>I suppose I could use "catch" and "throw", but that looks so much like "goto"
>that I feel sinful if I use that solution...

"Sinfulness" is a silly concept that quite a few folks in the computer
community have gotten into - a sort of aftereffect of structured programming.
The *real* reason for using higher-level constructs is efficiency, both
in programmer and execution time.

>Mike Maxwell

							stan shebs
							utah-cs!shebs